1. Field of the Invention
The invention relates generally to surgical implant systems. More particularly, the invention relates to shoulder arthroplasty systems and configurations for the components thereof.
2. Description of the Related Technology
It has become common to perform a shoulder arthroplasty to repair a patient's shoulder joint that has become dysfunctional due to disease or trauma. In a healthy shoulder, the humeral head is generally ball-shaped, and articulates within a socket formed by the scapula, called the glenoid cavity, to form the shoulder joint. Conventional implant systems for the total replacement of the shoulder joint (e.g., total shoulder arthroplasty (TSA)) generally replicate the natural anatomy of the shoulder, and include a metal humeral component having a stem which fits within the humeral canal, and an articulating head which articulates within the socket of a plastic glenoid component implanted within the glenoid of the scapula. The glenoid component can be either a single piece component that is attached to the glenoid, or a two-piece component having a plastic glenoid component attached to a metal baseplate, which is attached to the glenoid. In some cases, however, it is only necessary to replace a part of the shoulder joint, for example, by replacing the humeral head (e.g., a hemi shoulder arthroplasty (HAS)) with a prosthetic humeral head to articulate within the natural glenoid cavity of the scapula.
Recently, “reverse” type implant systems (e.g., total reverse shoulder arthroplasty (RSA)) have been developed in which the conventional ball-and-socket configuration that replicates the natural anatomy of the shoulder is reversed, such that a concave recessed articulating component is provided at the proximal end of the humeral component which articulates against a convex portion of a glenoid component. Such reverse shoulder implant systems are thought to provide an increased range of motion for treatment of glenoid humeral arthritis associated with irreparable rotator cuff damage, for example, by moving the center of rotation between the humeral component and the glenoid component to allow the deltoid muscles to exert a greater lever arm on the humerus.
It is sometimes necessary to convert from one type of implant system (e.g., TSA) to the other type of implant system (e.g., RSA), for example, when a patient does not react positively to an initially implanted system. Furthermore, it is sometimes necessary to replace components that have been implanted and are not functioning properly. Therefore, a need exists for arthroplasty systems and configurations of the components thereof.